Question: What is the greatest common factor of $2$ and $1$ ? Another way to say this is: $\operatorname{gcf}(2, 1) = {?}$
The greatest common factor is the largest number that is a factor of both $2$ and $1$ The factors of $2$ are $1$ and $2$ The only factor of $1$ is $1$ Thus, the greatest common factor of $2$ and $1$ is $1$. $\operatorname{gcf}(2, 1) = 1$